1. Technical Field
This invention relates generally to elastomeric seal lips bonded to metal substrates, and more particularly to methods of testing the bond strength of an elastomer seal lip to a metal substrate and test fixtures therefor.
2. Related Art
It is known to bond elastomeric seal lips to metal substrates in the construction of seals. This is typically the mechanism used to construct pistons for use in automatic transmissions. It is important while constructing the piston to ensure that the elastomeric seal lip is reliably bonded to the metal substrate of the piston to ensure the seal lip functions as intended in use. Accordingly, empirical testing is commonly performed in an effort to ensure the seal lip is being bonded to the desired specification.
Known testing mechanisms used to determine if a seal is properly bonded to the metal substrate are generally crude and provide test values of marginal repeatability and accuracy. The ability to obtain accurate and reliable test results is complicated due to the fact that the seal lip being tested can be difficult to grasp without causing damage to the seal lip, which in turn affects the accuracy of the test results. This is particularly troublesome when the seal lip is inclined in an oblique relation relative to a central axis of the seal. During testing it is important to grasp the seal lip in a manner that does not impact the ability to obtain reliable test results. As such, the mechanism used to grasp the seal lip must not over compress the seal lip, or the integrity of the seal lip could be compromised, e.g. initiation of a tear, thereby resulting in inaccurate tensile strength test results. In addition, the mechanism used to grasp the seal lip must not under compress the seal lip, or the mechanism will slip off the seal lip without obtaining true tensile strength results of the bond strength. Accordingly, great care must be taken during testing to ensure reliable and accurate test results are being obtained.